As a storage device in which a plurality of hard disk drives (HDDs) is handled as one logical volume, a redundant arrays of inexpensive disks (RAID) device is known. FIG. 19 is a diagram illustrating a configuration example of a RAID device 100.
As illustrated in FIG. 19, the RAID device 100 includes a controller module (hereinafter, referred to as a CM) 200 and a disk enclosure (hereinafter, referred to as a DE) 300. Further, the DE 300 stores a plurality of HDDs 400-1 to 400-5.
The CM 200 includes a RAID controller 210 and an input/output (I/O) controller 220. The RAID controller 210 primarily controls the entirety of the RAID device 100 and the I/O controller 220 primarily controls an input/output (command) with the HDDs 400-1 to 400-5.
In general, since an outer periphery of an embedded disk (platter) is more excellent than an inner periphery of the embedded disk in performance of the HDD, the HDD is used toward the inner periphery from the outer periphery of the disk. Note that, the reason why the outer periphery and the inner periphery of the disk are different from each other in performance is that the outer periphery has more bits per track than the inner periphery and a movement frequency between tracks by a magnetic head is low. In addition, one of the reasons is that a peripheral velocity of the outer periphery is higher than that of the inner periphery, and a reading/writing speed of the outer periphery by the magnetic head is higher than that of the inner periphery because a distance of the outer periphery is further than the inner periphery from a rotational shaft of the disk.
Note that, a related technology, there is a technology in which a spindle period control circuit is provided in a disk array device, spindle motors of a plurality of magnetic disk devices take rotational synchronization, and spindle motors of a plurality of other magnetic disk devices take rotational synchronization with a phase shifted from a phase of the plurality of magnetic disk devices. In the technology, a constraint is provided in an address conversion sequence to consecutively read/write data without being accompanied by rotational stand-by even in reading/writing throughout the track (see, for example, Patent Literature 1).
Further, as another related technology, there is a technology of selectively assigning a stripe of a plurality of lines along an axial direction to determine a previously selected storage area to a storage container including a plurality of storage areas along an axial direction of an additional axis (see, for example, Patent Literature 2).    [Patent Literature 1]: Japanese Laid-open Patent Publication No. 05-54546    [Patent Literature 2]: Japanese Laid-open Patent Publication No. 2006-120120
FIG. 20 is a diagram illustrating one example of failure rate of a near-line HDD depending on a physical location of a disk. In the RAID device, a use amount depending on the physical location of the disk of the HDD is more on the outer periphery than on the inner periphery in order to prioritize performance. As a result, as illustrated in FIG. 20, in particular, the failure rate depending on the physical location of the disk of the near-line HDD, which is cheap, and has a large capacity and low quality, is higher on the outer periphery than on the inner periphery.
However, a recovery time of the RAID device, when the HDD is faulty, follows a course of lengthening by an increase in processing time such as rebuilding or copying back of a logical volume accompanied by the recent large capacity of the HDD. Further, with the lengthening of the recovery time of the RAID device, an occurrence probability of multiple failures in which another HDD is faulty until a recovery of the RAID device also increases, and as a result, a data loss possibility by the multiple failures of the HDD increases. Further, as described above, a high failure rate of the outer periphery of the disk is also one cause of the increase in occurrence probability of the multiple failures of the HDD.
Note that, in each of the aforementioned related technologies, the aforementioned problems are not considered.